When the students at Sandy Hook Elementary School arrive at their new building Thursday, a familiar face will be there to greet them — their "new old principal."

Donna Page (pronounced Pa-jhay), the school's former principal, is leading the new school as interim principal, telling parents it was her "calling" to return after the tragedy. Parents have dubbed her the "new old principal" because Page was the school's leader for 14 years before retiring in 2010.

The school's principal Dawn Hochsprung was among the first victims of Adam Lanza's Dec. 14 rampage that left 20 children and six school staffers dead.

Once the Sandy Hook school had established that they would be able to use the former Chalk Hill Middle School building in nearby Monroe, Conn., parents knew that next biggest obstacle would be finding someone to lead the school through such a traumatic time.

"The next piece of the puzzle was, okay who is going to take the reins here? Who could possibly come in and fill Dawn Hochsprung's shoes?" parent Karen Dryer told ABCNews.com. "She was a truly amazing leader and friend. I worked very closely with her."

Dryer is a classroom volunteer in her 5-year-old son's kindergarten class at Sandy Hook Elementary School, and she has been helping the school prepare for Opening Day, as they call it, at the new building.

"We didn't think it was possible until we got a voicemail from Donna reintroducing herself and saying that when she heard [about the shooting] she knew it was the calling that she needed to come out of retirement and take the position of head of school," Dryer said.

"I started crying when I heard the message. It's still emotional," Dryer said and she cried again remembering the moment. "It was such a blessing and such an amazing relief because it was like, 'Oh my, now we can breathe. They're going to be okay.'"

Dryer's daughter, now a high school sophomore, was a student at the school when Page was principal and she knows her well.

"She's amazing. She's an extremely strong woman," Dryer said. "She is the perfect person to come in and take control and lead this school and staff forward."

"She could be a tough one, but she does everything completely out of love. That's why she stepped forward and came out of retirement. She loves the school, she loves the staff. The staff all know her and respect her and she knows a lot of the kids because she only just retired a couple of years ago."

Page has quickly stepped into her old position, taking charge by helming the round-the-clock effort to prepare the new building.

"I want parents and families enduring the loss of their precious children to know their loved ones are foremost in our hearts and minds as we move forward," Page wrote in a letter to the school community about the first day back to school. "We recognize your needs are paramount in our preparations and planning. Your strength and compassion has been, and will continue to be an inspiration to me and countless others as we work to honor the memory of your precious children and our beloved staff."

Students, families and teachers are participating in an open house today to visit the new school. Classes resume on Thursday.